As police commissioner, Ray Kelly fights terrorists — but as grand marshal of the St. Patrick’s Day Parade Wednesday, he marched with one.

Among the list of 14 honored “aides” to the grand marshal was Malachy McAllister, an Irish radical convicted of taking part in plots to kill to Belfast police officers in the 1980s.

McAllister lives in New Jersey and has been fighting US efforts to deport him for his past crimes and his former ties to the violent Irish National Liberation Army.

Despite this record, a group called the United Irish Counties nominated him to march with Kelly.

Parade organizers allowed McAllister to march after doing “due diligence” and after they “consulted with other parties in case of embarrassment,” said Hillary Burn, a spokesman. Burn would not say if Kelly was among those consulted.

When asked if Kelly knew he would be marching with McAllister, NYPD spokesman Paul Browne said: “[He] didn’t take it upon himself to investigate the backgrounds of the aides to the grand marshal.”